Using the Google maps geocode service to find the co-ordinates of an address

I've been having a lot of fun playing with Google maps this week. One of things we need to be able to do is map an address to a longitude and latitude so that we can display a point on a google map. This is very easy to do. Simply send a GET request to http://maps.google.com/maps/geo?q=<the address>&output=xml&key=<your key>. This returns a 'kml' XML document containing the geocode information. I simply used Visual Studio to create an XSD from the XML and then XSD.exe to generate the C# types to deserialize the XML document into. Here's the code:

using System;
using System.IO;
using System.Net;
using System.Web;
using System.Xml.Serialization;
namespace Mike.GoogleGeocode
{
    class Program
    {
        private const string googleGeocodeUrl = "http://maps.google.com/maps/geo?q={0}&output=xml&key={1}";
        private const string proxyUrl = "your proxy address";
        private const string key = "your key";
        static void Main()
        {
            const string address = "St. Julians, Sevenoaks, Kent, UK";
            var kml = GetKml(address);
            Console.WriteLine("Co-ordinates: {0}, for address: {1}", kml.Response.Placemark.Point.coordinates, address);
        }
        private static kml GetKml(string address)
        {
            var url = string.Format(googleGeocodeUrl, HttpUtility.UrlEncode(address), key);
            var request = (HttpWebRequest)WebRequest.Create(url);
            request.Accept = "text/xml";
            request.Method = "GET";
            // set the proxy if needed.
            request.Proxy = new WebProxy(
                proxyUrl, true, new string[0],
                CredentialCache.DefaultNetworkCredentials);
            kml kml;
            using (var response = request.GetResponse())
            using (var responseStream = new StreamReader(response.GetResponseStream()))
            {
                try
                {
                    var serializer = new XmlSerializer(typeof(kml));
                    kml = (kml)serializer.Deserialize(responseStream);
                }
                catch (Exception)
                {
                    kml = null;
                }
            }
            return kml;
        }
    }
}

Running it gives this result:

Which is the right location. One thing to watch out for is that the coordinates property is given as longitude, latitude, but Google maps expects you to enter co-ordinates as latitude, longitude. I was wondering why the API was resolving all my UK addresses to be off the East coast of Africa until I worked that out :P

You can download the full test solution here:

http://static.mikehadlow.com/Mike.GoogleGeocode.zip